| 1. |
- Abazov, V. M., et al.
(author)
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W gamma Production and Limits on Anomalous WW gamma Couplings in p(p)over-bar Collisions at root s=1.96 TeV
- 2011
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:24, s. 241803-
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Journal article (peer-reviewed)abstract
- We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W(-> l nu) + gamma production in e gamma and mu gamma final states. Using data corresponding to an integrated luminosity of 4.2 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process p (p) over bar -> W gamma + X -> l nu gamma + X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WW gamma couplings for data from hadron colliders: -0.4 < Delta kappa(gamma) < 0.4 and -0.08 < lambda(gamma) < 0.07 at the 95% C.L.
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| 2. |
- Abazov, V. M., et al.
(author)
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Measurement of the charge asymmetry in semileptonic B-s(0) decays
- 2007
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:15, s. 151801-
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Journal article (peer-reviewed)abstract
- We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic B-s(0) decays A(SL)(s,unt) by comparing the decay rate of B-s(0) -> mu(+) D-s(-) nu X, where D-s(-) -> phi pi(-) and phi -> K+K-, with the charge-conjugate (B) over bar (0)(s) decay rate. This sample was selected from 1: 3 fb(-1) of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain A(SL)(s,unt) = [1.23 +/- 0.97(stat) +/- 0.17(syst)] x 10(-2). Assuming that Delta m(s)/(Gamma) over bar (s) >> 1, this result can be translated into a measurement of the CP-violating phase in B-s(0) mixing: Delta Gamma(s)/Delta m(s) tan phi(s) = [2.45 +/- 1.93(stat) +/- 0.35(syst)] x 10(-2).
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| 3. |
- Abazov, V. M., et al.
(author)
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Measurement of the top quark mass in the lepton plus jets channel using the ideogram method
- 2007
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 75:9, s. 092001-
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Journal article (peer-reviewed)abstract
- A measurement of the top quark mass using events with one charged lepton, missing transverse energy, and jets in the final state, collected by the D0 detector from p (p) over bar collisions at root s=1.96 TeV at the Fermilab Tevatron collider, is presented. A constrained fit is used to fully reconstruct the kinematics of the events. For every event a top quark mass likelihood is calculated taking into account all possible jet assignments and the probability that an event is signal or background. Lifetime-based identification of b jets is employed to enhance the separation between t (t) over bar signal and background from other physics processes and to improve the assignment of the observed jets to the quarks in the t (1) over bar hypothesis. We extract a multiplicative jet energy scale (JES) factor in situ, greatly reducing the systematic effect related to the jet energy measurement. In a data sample with an integrated luminosity of 425 pb(-1), we observe 230 candidate events, with an estimated background of 123 events, and measure m(t)=173.7 +/- 4.4(stat+JES)(-2.0)(+2.1)(syst) GeV. This result represents the first application of the ideogram technique to the measurement of the top quark mass in lepton+jets events.
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| 4. |
- Abazov, V. M., et al.
(author)
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Search for a Higgs boson in diphoton final states with the D0 detector in 9.6 fb(-1) of p(p)over-bar collisions at root s=1.96 TeV
- 2013
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052007-
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Journal article (peer-reviewed)abstract
- We present a search for a Higgs boson decaying into a pair of photons based on 9.6 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The search employs multivariate techniques to discriminate signal from the nonresonant background and is separately optimized for a standard model and a fermiophobic Higgs boson. No significant excess of data above the background prediction is observed and upper limits on the product of the cross section and branching fraction are derived at the 95% confidence level as a function of Higgs boson mass. For a standard model Higgs boson with mass of 125 GeV, the observed (expected) upper limits are a factor of 12.8 (8.7) above the standard model prediction. The existence of a fermiophobic Higgs boson with mass in the 100-113 GeV range is excluded at the 95% confidence level.
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| 5. |
- Abazov, V. M., et al.
(author)
-
Search for neutral Higgs bosons in the multi-b-jet topology in 5.2 fb(-1) of p(p)over-bar collisions at root s=1.96 TeV
- 2011
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 698:2, s. 97-104
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Journal article (peer-reviewed)abstract
- Data recorded by the DO experiment at the Fermilab Tevatron Collider are analyzed to search for neutral Higgs bosons produced in association with b quarks. The search is performed in the three-b-quark channel using multijet-triggered events corresponding to an integrated luminosity of 5.2 fb(-1). In the absence of any significant excess above background, limits are set on the cross section multiplied by the branching ratio in the Higgs boson mass range 90 to 300 GeV, extending the excluded regions in the parameter space of the minimal supersymmetric standard model. (C) 2011 Elsevier B.V. All rights reserved.
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| 6. |
- Abazov, V. M., et al.
(author)
-
Search for production of single top quarks via tcg and tug flavor-changing-neutral-current couplings
- 2007
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:19, s. 191802-
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Journal article (peer-reviewed)abstract
- We search for the production of single top quarks via flavor-changing-neutral-current couplings of a gluon to the top quark and a charm (c) or up (u) quark. We analyze 230 pb(-1) of lepton+jets data from p (p) over tilde collisions at a center of mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We observe no significant deviation from standard model predictions, and hence set upper limits on the anomalous coupling parameters kappa(c)(g)/Lambda and kappa(u)(g)/Lambda, where kappa(g) define the strength of tcg and tug couplings, and Lambda defines the scale of new physics. The limits at 95% C.L. are kappa(c)(g)/Lambda < 0.15 TeV-1 and kappa(u)(g)/Lambda < 0.037 TeV-1.
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| 7. |
- Abazov, V. M., et al.
(author)
-
Search for randall-sundrum gravitons in dilepton and diphoton final states
- 2005
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 95:9, s. 091801-
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Journal article (peer-reviewed)abstract
- We report the first direct search for the Kaluza-Klein (KK) modes of Randall-Sundrum gravitons using dielectron, dimuon, and diphoton events observed with the D0 detector operating at the Fermilab Tevatron p (p) over bar Collider at root s = 1: 96 TeV. No evidence for resonant production of gravitons has been found in the data corresponding to an integrated luminosity of approximate to 260 pb(-1). Lower limits on the mass of the first KK mode at the 95% C. L. have been set between 250 and 785 GeV, depending on its coupling to standard model particles.
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| 8. |
- Abazov, V. M., et al.
(author)
-
Search for Resonant WW and WZ Production in p(p)over-bar Collisions at root s=1.96 TeV
- 2011
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:1, s. 011801-
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Journal article (peer-reviewed)abstract
- We search for resonant WW or WZ production by using up to 5: 4 fb(-1) of integrated luminosity collected by the D0 experiment in run II of the Fermilab Tevatron Collider. The data are consistent with the standard model background expectation, and we set limits on a resonance mass by using the sequential standard model W' boson and the Randall-Sundrum model graviton G as benchmarks. We exclude a sequential standard model W' boson in the mass range 180-690 GeV and a Randall-Sundrum graviton in the range 300-754 GeV at 95% C. L.
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| 9. |
- Abazov, V. M., et al.
(author)
-
Search for the Standard Model Higgs Boson in Associated WH Production in 9.7 fb(-1) of p(p)over-bar Collisions with the D0 Detector
- 2012
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 109:12, s. 121804-
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Journal article (peer-reviewed)abstract
- We present a search for the standard model Higgs boson in final states with a charged lepton (electron or muon), missing transverse energy, and two or three jets, at least one of which is identified as a b-quark jet. The search is primarily sensitive to WH -> lvb (b) over bar production and uses data corresponding to 9.7 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. We observe agreement between the data and the expected background. For a Higgs boson mass of 125 GeV, we set a 95% C.L. upper limit on the production of a standard model Higgs boson of 5.2 x sigma(SM), where sigma(SM) is the standard model Higgs boson production cross section, while the expected limit is 4: 7 x sigma(SM).
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| 10. |
- Abazov, V. M., et al.
(author)
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Measurement of angular correlations of jets at s=1.96 TeV and determination of the strong coupling at high momentum transfers
- 2012
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 718:1, s. 56-63
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Journal article (peer-reviewed)abstract
- We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance δR in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of δR and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb -1 collected with the D0 detector at the Fermilab Tevatron Collider in pp- collisions at s=1.96 TeV. The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV.
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